Mesophilic methane yield of ensiled switchgrass grown in Eastern Canada was assessed. Switchgrass was harvested at three stages of development, corresponding to mid-summer, late summer and early fall in 2007. The regrowth of plots harvested in mid-summer was also harvested in early fall as a two-cut strategy. Specific methane yields decreased significantly with crop maturity from 0.266 to 0.309 (N)L CH(4)g(-1) VS in mid-summer to 0.191-0.250 (N)L CH(4)g(-1) VS in early fall; values were similar for the first harvest in late July and the second harvest (regrowth) in October. Approximately 25% more methane was produced by hectare for the two-cut strategy (2.90-3.44 x 10(6)(N)L CH(4)ha(-1)) compared to the one-cut strategy with a harvest in late summer (2.28-2.77 x 10(6)(N)L CH(4)ha(-1)). Methane yields from switchgrass grown under the cool humid climate of Eastern Canada suggest that this crop remains an interesting renewable alternative energy source.
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